Flasher



July 16, 1940. C, H LARSQN v2,208,274

July 16, 1940- c. H. LARsoN FLASHER Filed Dec. 29, 1954 5 Sheets-Sheet 2July 16, 1940. c. H, LARsoN FLASHER Filed Dec. 29, 1934 3 Sheets-*Sheet3 l ar! HL W602i l MQW IParental July A16, 1940 2,208,274

UNITED STATES PATENT OFFICE 2,208,274 FLASHER Carl H. Larson, Elkhart,Ind., `assignor to The Adlake Company, a corporation of IllinoisApplication December 29, 1934, Serial No. 759,634

11 Claims. (Cl. 177-329) Highway crossing signals, particularly thoseterial. The details of mounting the coils on the used at railwaycrossings, must be highly reliable, panel I3 are unimportant here, andno further because the public is inclined to trust them imdescription isnecessary except to point out that plcitly. Unfortunately, however, nosignal is inthe relay coils I4 have iron cores I1 which, with 5'fallible, and the aim of the present invention is external ironconnectors I8 and the pole pieces 5 to minimize the danger that resultsfrom im- I5 and I6, form a magnetic circuit that is closed proper signaloperation, as for example when the except for the air gap between thepoles I5 and I6. control circuit fails, or when a lamp burns out. Thepoles I5 and I6 have vertical alined aper- Further and other objects andadvantages tures I9, and 2| adapted to receive a control l0 will becomeapparent as the disclosure proceeds circuit breaker or switch 22, andlamp circuit lo and the description is read in conjunction with breakers23 and 24, respectively. the accompanying drawings, in which The exactlocation of the air gap between the Fig. l is a diagrammatic View of aflasher made poles I5 and i6 is very important in obtaining inaccordance with this invention, the switch proper relay characteristics,and to this end, iron i5 parts being shown in the position they assumesleeves 25 are telescoped over the circuit breakers l5 just prior to theenergization of the control 23 and 2d to x the position of the air gap.The switch; construction of the control switch 22 is such that Fig. 2 isa similar view, but showing the switch an iron sleeve is not necessary.Spacer sleeves parts in the position they assume just prior to de- 2liof non-magnetic material are also telescoped go energization of thecontrol switch; over the circuit breakers 23 and 24 to protect the 20Fig. 3 is a similar View showing the position of otherwise exposedportions of the circuit break- .the switch parts when the controlcircuit is dead, ers and to hold the iron sleeves 25 in place. as forexample when a fuse in the control circuit These sleeves, as well as asimilar sleeve of nonhas been blown; magnetic material telescoped overthe control 25 Fig. 4 illustrates what takes place when the switch 22,serve the additional purpose of ric- 25 control switch is stuck inenergized position; tionally holding the switches in place within theFig. 5 illustrates the condition of the circuit iron circuit. when thecontrol switch is stuck in its raised THE CIBcUT BREAKERS pos1tion, asfor example when a short circuit 3o maintains the associated magnetsenergized; A Control switch 2g 30 Fig. 6 is a rear perspective viewshowing the physical form 0f the flasher relay; The control switch 22 isa slow acting back Fig. 7 is a horizontal, Sectional View 'taken 0ncontact switch (Fig. 1) and comprises a switch the line 'I-'I of Fig. 6.envelo-pe 30, preferably of glass, through the bot- It will beunderstood that the embodiment of tom of which electrodes 3l and 32 aresealed. 35 the invention shown in the drawings and the The centralelectrode SI is surrounded by a glass specic description which followsare for the purinsulating sleeve 33 for a portion of its length pose ofdisclosure only and Should not be Conand the pared end of the electrodeis bent over strued as imposing limitations 01'1 the appended with itsend 34 alongside the insulating sleeve 33.

40 Claims GXCBDG aS may be required by the prior art. The envelopecontains a quantity of mercury 40 35 which is adapted under certainconditions to HY RELA P SICA? Y l bridge the electrodes 3| and 32.Before describlrle theclrcults used 1n the flash- A displacer 36determines by its position within e1 relay 0f this lnVEIli'flOil, 1i?may be helpful 50 the switch envelope the level of the mercury and firstunderstand its physical OIIH- consequently the condition of the circuitthrough 45 The relay iS hOuSed Within a `Casing i0 (FigS- the switch. Itcomprises a sleeve 3l of magnetic 6 and 'D open at the back and hai/insavertical msteriaiclosed at its tsp by a thimbie 3s of poflarlge IIprovided with keyhole SIOS l2 (Only rous material. Preferably, thethimble is made one is shown) for securing the relay to a suitable of aCeramic material, known as .alundum, Support. The Operative Darts 0f therelay are which is manufactured by the Norton Company 50 mounted on apanel I3 which closes the front of of Worcester, Massachusetts. one ofthe three the casing IU and carries a plurality of relay coils principalgrades, RFA-84 Dense, RPA-360 Medi- I4, the upper two being associatedwith a top umand R-A-98 Coarse, may be selected accordpole piece I5, andthe lower two being associated ingto the specication of the switch. witha bottom pole piece IB, both of magnetic ma- `The rate of gas i'lowthrough the thimble may 55 be more accurately adjusted by applying dabsof cement to the thimble.

The plunger is guided in its vertical movement Iby washers 39 havingthree or more smoothly rounded lugs 44 engaging the walls of theenvelope.- The washers are held in place by springs 4i which serve toprotect the switch envelope during shipping.

Before the switch envelope is sealed o at 42, it is evacuated and filledwith an inert, ,or arc suppressing, gas (helium, hydrogen, heliumhydride, or the like).

The displacer 36 of the control switch 22 is adapted to reciprocatewithin the switch envelope at a predetermined rate of oscillation and inFig. 1, the switch parts are shown in the position which they assumejust before the circuit through the electrodes 3| and 32 'is closed. Itwill be noticed that the mercury level on the outside of the displacer36 is slightly higher than the mercury level on the inside of thedisplacer, this difference in level producing a slight gas pressuredifferential between the gas trapped within the displacer and that onthe outside. As the gas pressures tend to become equalized by the slowoutward passage of gas through the porous wall of vthe thimble 38, themercury level on the inside of the displacer slowly rises and that onthe outside slowly falls. As soon as the inside mercury level reachesthe end 34 of the electrode 3l, the circuit through the switch is closedand the relay coils i4 become energized. The displacer is then lifted tothe position shown in Fig. 2 drawing `up with it a column of mercury toa height such as indicated by the dotted line 43. Again, there is a gaspressure differential between the gas in the inside of the displacer andthat on the outside, but in this case,

the greater pressure is on the outside of the displacer so that there isa slow seepage of gas into the displacer. As the gas pressures tend tobecome equalized, the mercury level Yon the inside of the displacergradually falls and. that on the outside gradually rises until theinside mercury level falls below the end 34 of the electrode 3l,whereupon the relay coilsv I4 become deenergized and the displacer fallsbygravity to the position shown in Fig. 1, forcing the mercury level onthe inside down to the position indicated by the dotted line 44 (Fig.,1),

The above functioning of the control switch classifies. it as Aof theself-acting intermittent type, i. e., it automatically interrupts itsown circuit. i

In Fig. 2, the control switch 22 is shown just before the circuitbetween the electrodes. 3l and 32 is opened by the receding mercurycolumn within the displacer.

B. Lamp circuit breaker Z3 The lamp circuit breaker 23l is similar inmany respects to the control circuit breaker 22,

v but it functions quite differently. It comprises a switch envelope 45,electrodes 46 vand 41, a mercury fill 48 and a displacer generallydesignated 49, but the electrode 46 is somewhat shorter than theelectrode 3l, and the mercury ill 48 is such that when the displacer 49is 'completely out of the mercury as shown in Fig. 2, the circuitthrough the swtch is closed.

The displacer 49 comprises an iron sleeve 50 interiorly tted with anelongated glass thimble 5l having a small opening52 in its top wall. Thethimble is held in place within the iron sleeve 5U by springs 53 whichfrictionally engage the ends of the thimble which project beyond theiron sleeve and which also clamp guide washers 54 in place.

The top of the thimble 5I is packed with cotton wads 55 and 56, andbetween the two wads is a quantity of ceramic powder 5l. The two cottonwads and the powder serve the ysame purpose as the ceramic thimble 38 inthe control switch 22, i. e. they provide for a restricted flow of gasbetween the inside'andjoutside of the displacers The exact rate of flowinthe lamp circuitV breaker 23 may be adjusted by the quantities ofceramic powder and cotton used and the tightness with which they arepacked into the thimble. y i

'I'he lamp circuit breaker 23 functions as a front contact switch aslong as the intermittent energization of the relay coils I4 continuesabove a predetermined frequency. In such a case, the circuit through theswitch is closed Whenever the coils I4 are energized, see Fig. 2, andany mercury within the displacer when the latter is lifted by the coilsI4 falls away as soon as the outside mercury level drops below theVbottom of the sleeve 5I.

When the coils i4 are de-energized, the displacer falls by gravity tothe position shown in Fig. 1 forcing the mercury away from the centralelectrode 4S due to the compression of gas within the displacer. at thetop of the displacer is adjusted so that before the inside mercury levelhas a chance to make contact with the electrode 4B due to equalizationof the gas pressures on the inside and outside of the displacer, thecoils i4 have again become energized causing the displacer to be liftedto the position shown in Fig. 2.

If, however, the coils I4 are not energized within the time which ittakes for the inside mercury level to reach the central electrode 46, itis obvious that the circuit through the electrodes 48 and '4l rwill beclosed.

C. The lamp circuit breaker 24 This circuit breaker' normally functionsas a back contact switch, but in case the intermittent determinedfrequency, or in case a short circuit causes the coils tc becontinuously energized, the switch then functions as a front contactswitch and closes the circuit through the switch.

The switch comprises a glass envelope 58,

electrodes 59 and S, a mercury fill 6| and a dis-r placer generallydesignated 62, and' in general these parts resemble the correspondingparts of the two switches which have already been described. Thedisplacer S2 is substantially identical with the displacer 49 of thelamp circuit breaker 23, and in so far as the parts are the same, theywill be given corresponding reference characteristics, and will not befurther described.

The principal difference between the displacer 62 of the lamp circuitbreaker 24 and the displacer 49 of the lamp circuit breaker 23 is thatthe former is provided with an opening 63 through its side wall. As willbe seen from Fig. 1 when the switch 24 is in its cle-energized position,the circuit through the electrodes 59 and Bil is closed, thedisplacerthen being in its uppermost position and the openings E3 being justabove the mercury level. When the coils lll-are energized, the displaceris pulled down to the position shown inFig. 2 and the gas entrappedwithin the displacer forces the inside mercury level away Afrom thebaredend of the electrode The time delay element Venergization ofthe coils i4falls belowthe prev 59, thus` causing the circuit through the switch tobe opened. As gas slowly escapes through the time delay element from theinside of the displacer to the outside when the mercury level Within thedisplacer gradually rises but before it Ahas a chance to make contactwith the electrodeV 59, the relay coils I4 become de-enefrgized if thecontrol circuit is Working properly and the plunger 62 is lifted by itsbuoyancy to the position `shown in Fig. l, and any mercury which iscarried up within the displacer during its upward movement falls away assoon as the opening 63 rises above the outside mercury level so that themercury automatically levels off Whenever the relay coils I4 becomede-energized.

`Should the relay coils I4 for some reason fail I A. The @mm1 circuitThe control circuit is shown in light lines and functions tointermittently energize the relay coils I4. When the flasher is used ata railroad crossing, the local circuit is placed in operation Whenever atrain enters a given sectiony of track and short circuits the trackrelay 18 which includes a back Contact switch 1I associated with thecontrol circuit and a back contact switch 12 associated with the lampcircuit. The control circuit in practice is ordinarily energized by abattery i3 and the control switch 22 and relay coils i4 (connected inparallel) are in series With a battery 'I3 and the back contact switch1I of the track relay. The circuit can be traced from the battery 13through a conductor 14, switch 1I, conductor 15, electrode 3|, mercury35, electrode 32, conductors 16 and 11 to the relay coils I4 (the coilsare connected in parallel with one another) and back to the batterythrough conductor 18.

This circuit makes the control switch 22 a selfacting intermittentcircuit breaker whose rate of oscillation is determined by the rate ofgas flow through the time delay element 38.

B. Lamp circuit The lamp circuit is shown in heavy lines and includesthe lamp circuit breakers 23 and- 24, lamps and BI, the back contactswitch 12 of the track relay 1D and the secondary coil 82 of atransformer 83 which in .practice is ordinarily energized from a voltalternating current line.

The lamp 8U is controlled by the circuit breaker 23 and the lamp 8| bythe circuit breaker 24 and when the coils I4 are de-energized (as inFig. l) the circuit through the Ylamp 8l may be traced from thesecondary coil 82 of the transformer 83 through conductor 84, conductor85, electrode B0 of the switch 24, mercury 6I, electrode 59, conductor86, lamp 8l, conductor 81, back contact switch 12 of the track relay 18,and back to the secondary coil 82 through conductor 88.

When the relay coils I4 are energized, as in Fig. 2, the circuit throughthe lamp 80 may be traced' from the secondary coil 82 of the transformer83 through the conductor 84, conductor 89, electrode 41 of the switch23, mercury 48, electrode 46, conductor 98, lamp 88, conductor 81,backfcontact switch 12 of the track relay1 and back to 4the secondarycoil 82 through conductor 88.

OPERATION It has been pointed out that the control switch 22 functionsas a self-acting intermittent circuit breaker controlling theintermittent energization of the relay coils I4 which in turn actuatethe lamp circuit breakers 23 and 24, one of which functions ras a backcontact relay and the other as a front contact relay. As long as thecoils I4 are intermittently energized above a predetermined frequency,the lamps 80 and 8| will be alternately illuminated and the desiredflashing signal indication will be obtained.

Now let us suppose that for some reason, the control circuit shouldfail, as for example by theblowing of a fuse SI (Fig. 3,). The relaycoil'sj'il then vbecome permanently de-energized as distinguished fromintermittently de-energized, and the circuit breakers 23 and 24 take theposition shown in Fig. 3, in Which the electrical'circuits through bothswitches are closed.

Under these conditions, when a train approaches a protected crossing,the back contact switch 12 of the track relay 1I) is closed and both ofthe lamps 88 and 8l illuminated. This circuit relationship isparticularly desirableI because it illuminates both lamps in case thecontrolcircuit fails, and should one lamp be burned out, the other onewill still be illuminated. If an ordinary kfront contact switch wereused in place oi' the circuit breaker 23 and should the lamp SI beburned out when the control circuit failed, there would be no signalindication.

Another abnormal condition which may occur is for the control switch 22to be stuck in energized position, as for example when the current inthe local circuit' is insuiiicient tolift the displacer. In such a case,the coils i4 sta-y energizedi, and if the magnetic flux which theyproduce is suicient to operate the circuit breakers 23 and 24, theswitch parts will take the position shown in Fig. 4, or if the flux isnot sufficient to move the dislacers, they will take the positions shownin Fig. 3. In either case, the circuits through both of the lamps 88 and-8! are closed 'because whenever the displacers 48 and 82 are held inany position for more than a predetermined time interval, the circuitsthrough the respective switches will be closed. Here again, therefore,an additional safety factor is furnished because the circuits throughboth lamps are closed.

There are other conditions which might exist to cause the intermittentoperation of the lamp circuit breakers 23 and 24 to cease. For example,there might be a short circuit in the control circuit which would cutthe control switch 22 from the remainder of the circuit and thus causethe relay coils i4 to be permanently energized. This would occur in casethe wires 14 and 11 became crossed. The lamp circuit breakers would thenhold the position shown in Fig. 4 and the circuits through both lampswould be closed. it might also happen that some mechanical injury to theswitch would prevent the displacer 36 oi the control switch 22 fromfalling in which case the lamp circuit breakers 23 and 24 would take theposition shown in Fig. 1. Again, however, the circuits through bothlamps are closed. It will thus be seen that the ashing signal of thisinvention will provide a warning Signal as long as the lamp` circuitshave an electromotive force, andone. or the otherV of the lamps 80 and8l are operative. The failure of the controllcircuit .by any one of anumber of possible causes only stops the alternate dashing of the lamps,v

and when this condition exists, the circuits through both lamps areclosed. This is a distinct advantage over asher relays now on. themarket.

When the principles underlying the invention are iully understood, manymodications will suggest themselves to those skilled in the art` and theappended claims are to be construed as broadly as the prior art willpermit.

For convenience the switches 23 and 24 will be"Y identified in theappended claims accordingv to their Vnormal `functions, i. e., the`switch 23` will be called a front contact switch and the switch 2d aback contact switch.

The following glossary offterms vwill Serve to indicate the intendedconnotationsl for 'the terms: Circuit breaker--a switch for `selectivelybridging a gap betweentwo adjacent conductors which forni a part of anelectrical circuit; front contact circuit breakera circuit breaker asdefined above Ywhich is voperated by an electrical device which whenenergized bridges or tends to bridge the gap between the adjacentconductors associated with the circuit breaker; back contact circuitbreaker-a circuit breaker as defined above which is operated by anelectrical device which when deenergized bridges or tends to Vbridge thegap: between the adjacent conductors associated with the circuitbreaker;l synchro- `nisrn--the timed relationship between two or morethings which operate either simultaneously or in'cycles which bear atimed relationship with each other.

, I claim as my invention:

l. In a device of the class described, a control circuit including aself-acting intermittent circuit breaker, a main circuit including apair of lamps, means alternating illumination of the lamps comprising afrontA contact circuit breaker associated with one lamp and a backcontact circuit breaker associatedwith the other lamp, means in thecontrol circuit for operating the lamp circuit breakers in synchronismwith the control circuit breaker, and means for closing the circuitthrough one of the lamp circuit breakers whenever that one fails tooperate above a predetermined minimum number of cycles per unit of time.l I

2.V In a d evice of the class described, a control circuit including aself-acting intermittent circuit breaker, a main circuit including apair of lamps, front and back contact switch means associated with thelamps, means for alternately illuminating the lamps in response to thecontact switch means, means in the control circuit for operating thecontact switch means in-synchronism with the circuit breaker, and meansfor closing the circuit through at least one of the lamp switch meanswhenever the time rate of operation of said one switch means falls belowa predetermined value.

3. In a device of the class described, a control circuit including aself-acting intermittent circuit breaker, a main circuit including apair of lamps, front and back contact switch means associated with thelamps, means for alternately illuminating the lampslin response to thecontact switch means, means in the control circuit for operating thecontact switch means in synchronisrn with the circuit breaker, and meansfor closing the circuit through the switch means whenever the switchmeans fails to operate above a predetermined minimum number of cyclesper unit of time. l

4. In a device of the class described, a control circuit including aself-acting intermittent cir` cuit breaker, a main'circuit including apair of lamps, means for alternately illuminating.' the lamps includingfront and back Contact switches associated with the lamps andA operablein response to and in synchronism withfthe control circuitv breaker, andmeans including a time delay element constructed and arranged toilluminate both lamps in case the control circuit breaker fails tooperate. Y

5. In a device ofthe class described, Van interymittently energizedcontrol circuit, a main circuit including a pair of lamps, means foralternately illuminating the lamps in response to and mittentlyenergized control circuit, a main cir-j cuit including a pair rof lamps,means for alternatelyilluminating the lamps in response to and insynchronism with the intermittentA energization of the control circuit,and means for illuminating at least one oi the lamps in case theintermittentA energization of the control circuit fails, said meansincluding aswitch in the main circuit having a time delay elementconstructed and arranged so that if given suiiicient time to operatewill ciose the circuit through the switch regardless of the position ofthe switch parts within their range oi' relative movement andirrespective of whether the failure of the circuit is due to permanentenergization or permanent de-energization of the'control circuit.

7. In a device oi thev class described, an intermittently energizedcontrol circuit, a main circuit including a pair of lamps, meansincluding a front contact switch and a back contact switch foralternately illuminating the lamps in response to and in synchronismwith the intermittent energization of the control circuit, and means forilluminating both of the lamps in case the intermittent energization ofthe control circuit falls below a predetermined frequency.

8. In a device of the class described, a iiux responsive switch breakingupon de-energization and again closing after a short period of timeduringy said {ie-energization, a flux responsive switch breaking uponenergization and again closing after a short period of time during saidenergization, flux inducing means lalternately simultaneously energizingand de-energizing said switches at predetermined intervals, and signalmeans effective during the closure of the switches controlled by eachswitch..

9. In a device of the class'described, a flux responsive normally closedswitch breaking upon de-energization and again closing after a shortperiod of time, a flux responsive normally closed switch breaking uponenergization and again closing after a short period of time, fluxinducing means energizing and de-energizing said vswitches in vtimedrelation simultaneously, and

signal mea-nsl eective during the closure of the switches controlled byeach switch.

l0. In a device of the class described, aiflux responsive normally`closed switch breaking upon de-energization and returning'to `normalcondi-v tion after a short period of time, a lux responsive normallyclosed switch breaking upon energization and returning to normalcondition aftera short period of time, ux inducing means for energizingand de-energizing said switches in timed relation simultaneously, andsignal means effective during the closure of the switches controlled byeach switch.

11. In a device of the class described, a ux responsive quick breakingswitch closing after a period of energization, a uX responsive quickbreaking switch closing after a period of deenergization, iiux inducingmeans energizing and cle-energizing said switches at timed intervalssimultaneously, and signal means eiective during the closure of theswitches controlled by each switch.

CARL H. LARSON.

